France international Griezmann is being widely tipped to swap Atletico for Premier League giants United in the off-season.
Saul, however, believes the 26-year-old forward can be replaced if he opts to leave the Spanish capital.
"In the end, Antoine Griezmann can manage his future as he wishes," Saul said via Marca and AS Diario.
"He is with us. We are waiting for him in pre-season and finally his future he will decide.
"If Antoine Griezmann leaves we have [Fernando] Torres, [Kevin] Gameiro, [Angel] Correa and [Yannick] Carrasco.
"He is a very important player for us, we know the quality he has, but most importantly no one player is above the club."